ECDC/EFSA Quarterly Avian Influenza Overview March-June 2025

 
#18,770

Every 3 months the ECDC publishes a highly detailed avian influenza surveillance report, and while they tend to be EU centric, in its 65 pages you'll find ample coverage of outbreaks and infections from around the world on a wide variety of avian subtypes.

Four years ago, following a complex series of genetic changes to the HPAI H5 virus, we began to see a global surge and spread of H5N1, characterized by increased spillovers into mammals (mink, foxes, marine mammals, and eventually even cattle).

These highly detailed quarterly reports make excellent reference material, well worth perusing. I've posted the ECDC summary and link below. I'll have a brief postscript after the break.

Avian influenza overview March–June 2025 

European Food Safety Authority,
European Centre for Disease Prevention and Control,
European Union Reference Laboratory for Avian Influenza, Leonidas
Alexakis, Hubert Buczkowski, Mariette Ducatez, Alice Fusaro, Jose L Gonzales, Thijs Kuiken, Gražina Mirinavičiūtė, Karl Ståhl, Christoph Staubach, Olov Svartström, Calogero Terregino, Katriina Willgert, Miguel Melo and Lisa Kohnle

Abstract

Between 8 March and 6 June 2025, 365 highly pathogenic avian influenza (HPAI) A(H5) virus detections were reported in domestic (167) and wild (198) birds across 24 countries in Europe. HPAI A(H5N1) virus detections were predominant and mainly located in western, central and south-eastern Europe. Most detections in wild birds concerned waterfowl, particularly swans and geese, but also gulls were involved. Poultry establishments, particularly domestic ducks and chickens, continued to be affected in large numbers in Hungary and Poland. 

In mammals, HPAI A(H5N1) and A(H5N5) virus detections were reported in a domestic cat, red foxes, Eurasian otters and grey seals. For the first time ever, HPAI A(H5N1) viral infection was detected in a sheep in the United Kingdom. Outside Europe, the United States of America (USA) continued to report A(H5N1) virus detections in dairy cattle, while the virus was found for the first time in a gray fox (USA), a leopard cat (South Korea) and a long-tailed weasel (USA). 

Between 8 March and 6 June 2025, 20 cases of avian influenza virus infection in humans, including four deaths, were reported in six countries: Bangladesh (two A(H5N1) cases), Cambodia (two A(H5N1) cases), China (one A(H10N3), one A(H5N1), and 11 A(H9N2) cases), India (one A(H5N1) case), Mexico (one A(H5N1) case), and Viet Nam (one A(H5N1) case). Most of the A(H5N1) human cases (n = 5/8) reported exposure to poultry prior to detection or onset of illness. Given the widespread circulation of avian influenza viruses in animal populations, human infections remain rare. No human-to-human transmission has been documented during the reporting period. 

The risk of infection with the avian A(H5) clade 2.3.4.4b influenza viruses currently circulating in Europe remains low for the general public in the European Union/European Economic Area (EU/EEA) and low-to-moderate for those occupationally or otherwise exposed to infected animals or contaminated environments.

As impressive as these quarterly reviews are, they can only provide us with an overview. Surveillance and reporting has it's limits - even in higher resource European nations - and this report reflects only what countries were willing or able to publicly divulge.

While HPAI H5 avian flu is believed to be present in most nations (excluding Australia/NZ), the following map shows that vast swaths of the globe are not reporting outbreaks.

Surveillance and testing, even in countries that are releasing data, is often limited. 

As far as human cases are concerned, last summer the ECDC published Enhanced Influenza Surveillance to Detect Avian Influenza Virus Infections in the EU/EEA During the Inter-Seasonal Period which cautioned:

Sentinel surveillance systems are important for the monitoring of respiratory viruses in the EU/EEA, but these systems are not designed and are not sufficiently sensitive to identify a newly emerging virus such as avian influenza in the general population early enough for the purpose of implementing control measures in a timely way.

While the risk assessments provided in this overview (low or very low for the general public) seem reasonable based on the data available, confidence in the quality and completeness of that data is difficult to gauge.

Which is why - despite recent slowdowns in reported cases - we can't afford to become complacent.